WASHINGTON 
It's not quite over yet. Democrats hit a snag Thursday in their drive to rush through a package of fixes to the big health care law signed by President Barack Obama, but they still hoped for final passage in yet another late-night session.

House Majority Leader Steny Hoyer said that if the Senate finished its work by afternoon, as expected, the House would immediately take up the bill. Democrats are saying they do not expect any major problems - but they're also keeping their fingers crossed.

Senate leaders had planned to complete work on the fix-it bill by midday Thursday and get it quickly to Obama. But Republicans established that they would be able to kill some language in the bill that relates to grants for low-income college students. That meant the altered bill would have to be returned to the House - four days after House members thought they'd seen the last of it late Sunday night.

Senators who had been in session past 2 a.m. Thursday returned to work on a long list of proposed Republican amendments.

The president, who signed the separate landmark legislation into law on Tuesday, was flying to Iowa for an afternoon speech, the first of many appearances around the country to sell his health care revamp before the fall congressional elections.

Obama was appearing in Iowa City, where as a presidential candidate in 2007 he touted his ideas for health coverage for all. His trip comes as polls show people are divided over the new law, and Democratic lawmakers hope he can convince more voters by November that their support was the right move.

Meanwhile, House Speaker Nancy Pelosi, D-Calif., voiced concern over warnings of violent reprisals against members of Congress who voted for the overhaul.

She said the response has "no place in a civil debate in our country." Republicans, too, went to the House floor to plead with opponents of the health care law to refrain from violence and threats.

The FBI is working with lawmakers subjected to menacing obscenity-laced phone messages. In some instances, bricks were hurled at congressional offices, including Rep. Louise Slaughter's district headquarters in Niagara Falls, N.Y.

As an exhausted Senate labored into the wee hours Thursday on a stack of GOP amendments to the follow-up bill, Jim Manley, spokesman for Senate Majority Leader Harry Reid, told reporters that Republicans consulting with the chamber's parliamentarian had found "two minor provisions" that violate Congress' budget rules.

Republicans have been hunting for such violations in hopes of bringing down the legislation. Democrats had also been consulting with the parliamentarian, Alan Frumin, and hoped they had written a measure that would not be vulnerable to such problems.

The two provisions were expected to be formally removed from the bill on Thursday. Manley said he expected the Senate to approve the measure without them and send it to the House. He said Senate leaders, after conversations with top House Democrats, expect the House to approve the revised measure.

Both chambers are hoping to begin a spring recess by this weekend.

"This is quite benign. ... Of all the things they could have sent back this is probably the most benign," Pelosi told reporters.

Besides reshaping parts of the landmark health overhaul, the legislation transforms the federal student loan program - in which private banks distribute the money - into one in which the government issues the loans directly. That produces some federal savings, which the bill uses in part to increase Pell grants to needy students.

Democratic aides said the problematic provisions deal with safeguarding students from future cuts in their grants if Congress does not provide enough money for them. The provisions violate budget rules because they do not produce savings, one aide said.

The development came as the Senate completed nine hours of uninterrupted voting on 29 GOP amendments to the legislation. Majority Democrats defeated every amendment.

The legislation would change the new health care law by making drug benefits for Medicare recipients more generous by gradually closing a gap in coverage, increasing tax subsidies to help low-income people afford health care, and boosting federal Medicaid payments to states.

It kills part of the new statute uniquely giving Nebraska extra Medicaid funds - designed to lure support from that state's Sen. Ben Nelson - that had become a glaring embarrassment to Democrats. It also eases a new tax on expensive health coverage bitterly opposed by unions and many House Democrats, while delaying and increasing a new levy on drug makers.

As they began pushing the bill to passage on Wednesday afternoon, Democrats ran into a mountain of GOP amendments. Outnumbered and all but assured of defeat, Republicans forced votes on amendments aimed at reshaping the measure - or at least forcing Democrats to take votes that could be used against them in TV ads in the fall campaigns.

"The majority leader may not think we're serious about changing the bill, but we'd like to change the bill, and with a little help from our friends on the other side we could improve the bill significantly," said Senate Minority Leader Mitch McConnell, R-Ky.

By 57-42, Democrats rejected an amendment by Sen. Tom Coburn, R-Okla., barring federal purchases of Viagra and other erectile dysfunction drugs for sex offenders. Coburn said it would save millions of dollars, while Sen. Max Baucus, D-Mont., called it "a crass political stunt."

The landmark legislation that Obama signed Tuesday would provide health care to 32 million uninsured people, and make coverage more affordable to millions of others by expanding the reach of Medicaid and creating new subsidies. Insurance companies would be forbidden to refuse coverage to people with illnesses, individuals could buy policies on newly created exchanges and parents could keep children on their family plans until their 26th birthdays.

The $938 billion, 10-year price tag would be financed largely by culling savings from Medicare and imposing new taxes on higher income people and the insurance, drug and medical device industries.